/*
** $Id: lcorolib.c,v 1.5 2013/02/21 13:44:53 roberto Exp $
** Coroutine Library
** See Copyright Notice in lua.h
*/


#include <stdlib.h>


#define lcorolib_c
#define LUA_LIB

#include "lua.h"

#include "lauxlib.h"
#include "lualib.h"


static int auxresume (lua_State *L, lua_State *co, int narg) {
	int status;
	if (!lua_checkstack(co, narg)) {
		lua_pushliteral(L, "too many arguments to resume");
		return -1;  /* error flag */
	}
	if (lua_status(co) == LUA_OK && lua_gettop(co) == 0) {
		lua_pushliteral(L, "cannot resume dead coroutine");
		return -1;  /* error flag */
	}
	lua_xmove(L, co, narg);
	status = lua_resume(co, L, narg);
	if (status == LUA_OK || status == LUA_YIELD) {
		int nres = lua_gettop(co);
		if (!lua_checkstack(L, nres + 1)) {
			lua_pop(co, nres);  /* remove results anyway */
			lua_pushliteral(L, "too many results to resume");
			return -1;  /* error flag */
		}
		lua_xmove(co, L, nres);  /* move yielded values */
		return nres;
	}
	else {
		lua_xmove(co, L, 1);  /* move error message */
		return -1;  /* error flag */
	}
}


static int luaB_coresume (lua_State *L) {
	lua_State *co = lua_tothread(L, 1);
	int r;
	luaL_argcheck(L, co, 1, "coroutine expected");
	r = auxresume(L, co, lua_gettop(L) - 1);
	if (r < 0) {
		lua_pushboolean(L, 0);
		lua_insert(L, -2);
		return 2;  /* return false + error message */
	}
	else {
		lua_pushboolean(L, 1);
		lua_insert(L, -(r + 1));
		return r + 1;  /* return true + `resume' returns */
	}
}


static int luaB_auxwrap (lua_State *L) {
	lua_State *co = lua_tothread(L, lua_upvalueindex(1));
	int r = auxresume(L, co, lua_gettop(L));
	if (r < 0) {
		if (lua_isstring(L, -1)) {  /* error object is a string? */
			luaL_where(L, 1);  /* add extra info */
			lua_insert(L, -2);
			lua_concat(L, 2);
		}
		return lua_error(L);  /* propagate error */
	}
	return r;
}


static int luaB_cocreate (lua_State *L) {
	lua_State *NL;
	luaL_checktype(L, 1, LUA_TFUNCTION);
	NL = lua_newthread(L);
	lua_pushvalue(L, 1);  /* move function to top */
	lua_xmove(L, NL, 1);  /* move function from L to NL */
	return 1;
}


static int luaB_cowrap (lua_State *L) {
	luaB_cocreate(L);
	lua_pushcclosure(L, luaB_auxwrap, 1);
	return 1;
}


static int luaB_yield (lua_State *L) {
	return lua_yield(L, lua_gettop(L));
}


static int luaB_costatus (lua_State *L) {
	lua_State *co = lua_tothread(L, 1);
	luaL_argcheck(L, co, 1, "coroutine expected");
	if (L == co) lua_pushliteral(L, "running");
	else {
		switch (lua_status(co)) {
		case LUA_YIELD:
			lua_pushliteral(L, "suspended");
			break;
		case LUA_OK: {
			lua_Debug ar;
			if (lua_getstack(co, 0, &ar) > 0)  /* does it have frames? */
				lua_pushliteral(L, "normal");  /* it is running */
			else if (lua_gettop(co) == 0)
				lua_pushliteral(L, "dead");
			else
				lua_pushliteral(L, "suspended");  /* initial state */
			break;
					 }
		default:  /* some error occurred */
			lua_pushliteral(L, "dead");
			break;
		}
	}
	return 1;
}


static int luaB_corunning (lua_State *L) {
	int ismain = lua_pushthread(L);
	lua_pushboolean(L, ismain);
	return 2;
}


static const luaL_Reg co_funcs[] = {
	{"create", luaB_cocreate},
	{"resume", luaB_coresume},
	{"running", luaB_corunning},
	{"status", luaB_costatus},
	{"wrap", luaB_cowrap},
	{"yield", luaB_yield},
	{NULL, NULL}
};



LUAMOD_API int luaopen_coroutine (lua_State *L) {
	luaL_newlib(L, co_funcs);
	return 1;
}

